1. Field of the Invention
The present invention relates to a mesh of parallel glass strands which is useful as a reinforcement material for organic mixtures.
2. Description of the Background Art
Glass strands can be used in many ways for reinforcing thermosetting or thermoplastic organic substances. When composite articles produced from reinforced substances of this type are to be mechanically stressed during their intended use, the article is typically formed from glass strands oriented in a preferred direction. An article of this type is often produced by the impregnation, with an organic substance, of a plurality of layers of glass strands which are in the form of unidirectional sheets.
The production of complex reinforced composite articles of this type comes up against several difficulties, however. The first problem lies in the fact that the strands constituting the sheets may be deformed or displaced relative to one another during the handling operations which take place between the moment when the glass sheets are manufactured and the moment when the composite element is produced.
In order to solve this problem, it is known, according to French patent FR-A-2 594 858, incorporated herein by reference, to produce a sheet of parallel strands, for example, glass strands, which are assembled with the aid of hot-melting binding strands. A sheet is produced, the strands of which cannot be displaced relative to one another, owing to a heat treatment which melts the binding strands and thereby brings about bonding between the glass strands. After this treatment, the sheet can be handled or cut up without risk of deformation. The rigidity thus conferred on such a sheet hampers, however, any further deformation to which it would be desirable to subject it during the production of a composite article.
The second difficulty lies in the production of a complex composite article in which parallel reinforcements are oriented in at least two different directions in a plane in order to follow the shape of the said article. In fact, an article of this type currently requires the juxtaposition of at least two sheets of parallel reinforcements in two different orientations. This division of reinforcements results in a discontinuity at the transition from one sheet to the other. Whether the region in which the discontinuity is disposed in is on the surface or within the body of the composite article, if it is subjected to stresses, overstressing will appear in this region with a consequent risk of rapid degradation of the material. Moreover, the different orientations of the reinforcing sheets also lead to overstressing along the entire periphery of the article of composite material.